Optical sight assembly

ABSTRACT

An optical assembly (10) includes a first plurality of optical elements (14) providing the viewer a first field of view and a second plurality of optical elements (18) that, when moved into the optical path (16), provides the viewer with a second field of view. A support structure (36) for the second plurality of optical elements (18) includes a permanent magnet (64) that is disposed to cause a switch (66) located on the housing (12) of the optical assembly (10) to close. The changing of the position of the switch (66) results in a signal being provided to identify to the viewer which field of view is being presented by the assembly (10).

BACKGROUND OF THE INVENTION

The present invention generally relates to an optical assembly and, inparticular, relates to one such assembly having means for selectingdifferent optical fields of view and means for magnetically signallingthe viewer which of the different optical fields of view is selected.

There are many optical assemblies wherein it is highly desirable andadvantageous to have more than one optical field of view available tothe operator. Under many such some circumstances however, it is thencritical that the operator correctly and reliably know exactly whichoptical field of view has been selected.

Quite often however, such circumstances are usually accompanied by otherdifficulties as well. For example, one such circumstance may be abattlefield. Under battlefield conditions it is highly advantageous tohave an optical sight that has both a wide field of view and a narrowfield of view available to the user. For example, it is quiteadvantageous for a gunner to be able to select a target over a widerange of distances. Hence, an optical sight having one set of opticalelements having a wide field of view, for relatively closer rangetargets and a second set of optical elements which, when positioned inthe optical path of the first set of optical elements, presents a narrowfield of view, for relatively distant targets, provides a gunner withthe ability to select, track and/or attack targets over a large tacticalbattlefield. It follows, naturally, that for such an optical assembly tobe effective it is critical that the operator of the sight must knowwhich optical field of view is in use when a target is being selected.Conventionally, this is accomplished by sophisticated electroniccircuitry. However, under modern battlefield conditions, it must beanticipated that all equipment in the field will be subjected topotentially damaging and interfering forms of electromagnetic energyinterference (EMI) and radio frequency energy interference (RFI). Suchenergy interference is known to interfere with electronic circuitry tothe end that either the circuitry becomes unreliable or ceases tofunction. At best, either of these conditions render the advantages of amultiple field of view optical assembly ineffective. In the worst case,such energy interference can cause the electronic circuitry to yielderroneous outputs, thereby causing the user to misjudge the distance toa target, i.e., the user may aim far beyond a close target if anerroneous signal indicates that the telescope path is being used.

Consequently, it is highly desirable to provide an optical assembly thatnot only is capable of presenting the viewer with different opticalfields of view but also provides a reliable indication to the viewer asto which field of view is currently in use regardless of the presence ofEMI or RFI.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide anoptical sight assembly that overcomes the above-recited difficulties ofconventional multiple optical fields of view assemblies.

This object is accomplished, at least in part, by an optical assemblyhaving means for selecting the optical field of view presented to theviewer and means for magnetically indicating which optical field of viewis being presented.

Other objects and advantages will become apparent to those skilled inthe art from the following detailed description of the invention read inconjunction with the attached drawings and the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing, not drawn to scale, includes:

FIGS. 1A and 1B which are a schematic diagrams of an optical assemblyembodying the principles of the presented invention;

FIG. 2 which is a perspective diagram of the optical assembly shown inFIG. 1; and

FIG. 3 is a cross-sectional view of the optical assembly taken along theline 3--3 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

An optical assembly, generally indicated at 10 in the drawings andembodying the principles of the present invention, includes a housing 12having a first plurality of optical elements 14 defining an optical path16 having a first field of view, a second plurality of optical elements18, means 20 for selectively introducing the second plurality of opticalelements 18 into the optical path 16 such that a second field of view isestablished therealong, and means 22 for providing a magnetic signalindicative of the position of the second plurality of optical elements18. Preferably, the optical assembly 10 also includes an eyepiecesection 24 having a reticle 26 associated therewith. FIGS. 1a and 1bdepict one view of the invention with the second plurality of opticalelements in the optical path (FIG. 1a) and another view with theseelements rotated out of the optical path (FIG. 1b). FIG. 1a depicts anembodiment useful in a wide field of view application while FIG. 1bdepicts a narrow field of view application. The ray paths illustrated inFIGS. 1a and 1b are for illustration only and it will be understood bythose skilled in the art that the illustrated ray paths are indicativeof what the detector at light viewing end 30 "sees". (The rest of thelight rays entering, for example, member 32 are not illustrated).Further, in one embodiment, for example as shown in FIG. 2, the opticalassembly 10 can also include an infrared image converter 15 disposedbetween the first plurality of optical elements 14 and the eyepiecesection 24. As known in the art, an infrared image converter changes anincoming infrared image to an image that is visible to the operator.

In one preferred embodiment, the housing 12 is generally cylindrical incross-section having different cross-sectional diameters to accommodatevarious diameters of the first plurality of optical elements 14. It willbe understood that the housing 12 could have many other cross-sectionalshapes, including, for example, a square, rectangle or elliptical shape.The housing 12 includes a light receiving end 28 and a light viewing end30. As shown in FIGS. 1A and 1B, the housing 12 is sealed at the lightreceiving end 28 thereof by one member 32 of the first plurality ofoptical elements 14 and is adapted to accommodate, in a sealing mannerthe eyepiece section 24 at the light viewing end 30. In one embodiment,the housing 12 is formed from high impact plastic, although many othermaterials could also be used.

As shown in the Figures the first plurality of optical elements 14defining the first optical path 16 are fixed within the housing 12 alongthe optical path 16 of the assembly 10. In the preferred embodiment, thefirst plurality of optical elements 14 are selected to provide a viewerwith a wide angle field of view.

As shown in FIG. 2, the second plurality of optical elements 18 are, inthe preferred embodiment, arranged within a support structure 34. Thesupport structure 34 is preferably disposed within the housing 12 sothat the second plurality of optical elements 18 can be moved into theoptical path 16 by the means 20 from outside the housing 12 and readilyaccessible to the operator. Preferably, the second plurality of opticalelements 18 are disposed at first and second ends, 36 and 38,respectively, of the support structure 34. Such an arrangement, by thesecond plurality of optical elements 18 supporting both ends, 36 and 38,of the support structure 34, allows lightweight material to be used inthe construction of the support structure 34. If, for example, all ofthe second plurality of optical elements 18 were disposed at one end 36of the support structure 34, then the support structure 34 would requirea more rigid material. In the embodiment shown, the support structure 34includes openings 40 through the wall 42 thereof, the openings 40 beingdisposed such that when the second plurality of optical elements 18 arepositioned out of the optical path 16 of the assembly 10, light enteringthe light receiving end 28 of the housing 12 reaches the eyepiecesection 24 via the first plurality of optical elements 14 along theoptical path 16 without interference.

As shown in FIG. 3, the support structure 34 for the second plurality ofoptical elements 18 further includes first and second shaft sections, 44and 46, respectively, each having a first end, 48 and 50, respectively,affixed to the wall 42 of the support structure 34 opposite each other.A second end 52 of the first shaft section 44 distal the wall 42 of thesupport structure 34 extends through an opening 54 in the housing 12 andis provided with a knob 56 or other means to allow the operator torotate the support structure 34. In the embodiment shown, a second end58 of the second shaft section 46 distal the wall 42 of the supportstructure 34 terminates within the housing 12 in a recess 60 sized toaccept the second end 56. The recess 60 is disposed opposite the opening54 through which the first shaft section 44 passes and is sized to allowthe second end 58 of the second shaft section 46 to rotate therein.

The support structure 34 also, in the preferred embodiment, includes themeans 22 for providing a magnetic signal indicative of the position ofthe second plurality of optical elements 18. In the embodiment shown,the means 22 includes a permanent magnet 62 affixed to wall 42 of thesupport structure 34. In addition, the means 22 includes a magneticallyactuated switch 64 affixed to the housing 12. In the embodiment shown inthe figures, the magnetically actuated switch 64 is disposed in a slot66 formed in the housing 12. Preferably, the magnetically actuatedswitch 64 is a reed switch and includes first and second contacts, 68and 70, respectively. In the operation of the embodiment shown, thecontacts, 68 and 70, of the switch 64 are spaced apart when the supportstructure 34 is positioned such that the second plurality of opticalelements 18 are out of the optical path 16, i.e., during wide field ofview operation. When the support structure 34 is rotated to position thesecond plurality of optical elements 18 into the optical path 16, i.e.,during narrow field of view operation, the permanent magnet 62 rotateswith the wall 42 of the support structure 34 to become sufficientlyproximate the slot 66 in the housing 12 to cause the contacts, 68 and70, to close thereby making electrical contact with each other. Theposition of the first and second contacts, 68 and 70, is monitored by aconventional signal processing circuitry 72 that, in the preferredembodiment, provides a signal to field of view indicator 74 disposed onthe reticle 26 within the eyepiece section 24. Hence, the operator can,without changing position with respect to the eyepiece section 24, knowwhich field of view is being presented.

Advantageously, then, it will be recognized that the assembly 10described herein is not susceptible to either EMI or RFI effects andthat the magnetically actuated switch 64 will close only when subjectedto the magnetic field of the permanent magnet 62 on the supportstructure 34.

Although the optical assembly 10 has been described herein with respectto a particular embodiment, it will be understood that other arrangementand configurations may be provided that nonetheless do not depart fromthe spirit and scope of the present invention. For example, instead of asecond plurality of optical elements, the narrow field of view may beaccomplished by the use of a single optical element. Hence, the presentinvention is deemed limited only by the appended claims and thereasonable interpretation thereof.

What is claimed is:
 1. An optical assembly comprising:a housing; a firstplurality of optical elements, said first plurality of optical elementsbeing disposed within said housing and defining an optical path; atleast one second optical element, said at least one second opticalelement being disposed within said housing; means for selectivelyintroducing or removing said at least one second optical element to orfrom said optical path, wherein said at least one second optical elementis disposed within a support structure, wherein said means forselectively introducing or removing said support structure includesfirst and second shaft sections affixed to a wall of said supportstructure, said first shaft section and said second shaft section beingdisposed on said wall opposite each other such that said supportstructure can be rotated, wherein said support structure is adapted tobe rotated within said housing by said selectively introducing orremoving means such that said at least one second optical element isselectively introduced into or removed from said optical path; and meansfor magnetically indicating the position of said at least one secondoptical element within said housing.
 2. The assembly as claimed in claim1, further comprising:an eyepiece section through which a view along theoptical path is presented to an operator of said assembly.
 3. Theassembly as claimed in claim 2, further comprising:means, disposedbetween said first plurality of optical elements and said eyepiecesection, for converting an infrared image to a visible image.
 4. Theassembly as claimed in claim 2, wherein said first plurality of opticalelements presents a comparatively wide field of view to the operator. 5.The assembly as claimed in claim 4, wherein said at least one secondoptical element presents, when disposed in said optical path and incombination with said first plurality of optical elements, acomparatively narrower field of view to the operator.
 6. The assembly asclaimed in claim 1 wherein said first shaft section extends through saidhousing such that it is accessible to an operator and said second shaftsection terminates within said housing.
 7. The assembly as claimed inclaim 6, wherein said second shaft section terminates in a recess insaid housing, said recess being sized to permit said second shaftsection to rotate therewithin.
 8. The assembly as claimed in claim 1,wherein said magnetically indicating means includes a permanent magnetaffixed to said support structure such that the position of saidpermanent magnet changes when said support structure is rotated.
 9. Theassembly as claimed in claim 1, wherein said magnetically indicatingmeans further includes a magnetically actuated switch, affixed to saidhousing and a permanent magnet affixed to said support structure suchthat when said at least one second optical element is disposed in saidoptical path said permanent magnet is proximate said magneticallyactuated switch and when said at least one second optical element isdisposed outside of said optical path, said permanent magnet is distalsaid magnetically actuated switch.
 10. The assembly as claimed in claim9, wherein said magnetically actuated switch is a reed switch.
 11. Theassembly as claimed in claim 9, wherein said magnetically actuatedswitch is disposed within a recess in said housing.
 12. The assembly asclaimed in claim 1, further comprising an eyepiece section through whichan operator can look along said optical path of said assembly.
 13. Theassembly as claimed in claim 12, wherein said eyepiece includes meansfor indicating the position of said support structure within saidhousing.
 14. The assembly as claimed in claim 13, wherein said positionindicating means is a reticle.